title: Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae).
abstract: BACKGROUND
  Five formulated insecticides (lambda-cyhalothrin at 10 mg m⁻², bifenthrin at 50 mg m⁻², fipronil at 10 mg m⁻², fenitrothion at 50 mg m⁻², imidacloprid at 5 mg m⁻²) and one active ingredient (DDT at 500 mg m⁻²) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda-cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed.
  
  
  RESULTS
  The order of susceptibility of different stages of bed bugs was as follows: early stage-lambda-cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage-lambda-cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult-lambda-cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT₅₀ among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects.
  
  
  CONCLUSIONS
  Lambda-cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post-treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation.
authors.affiliation: Urban Entomology Laboratory, Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia.
authors.forename: Yee-Fatt
authors.initials: YF
authors.lastname: How
authors.forename: Chow-Yang
authors.initials: CY
authors.lastname: Lee
mesh_terms: D000818:Animals; D001511:Bedbugs / Q000187:drug effects* / Q000254:growth & development* / Q000502:physiology; D003634:DDT / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D005278:Fenitrothion / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007306:Insecticides / Q000494:pharmacology*; D008018:Life Cycle Stages / Q000187:drug effects*; D008297:Male; D000073943:Neonicotinoids; D009570:Nitriles / Q000494:pharmacology; D009574:Nitro Compounds / Q000494:pharmacology; D010574:Pesticide Synergists / Q000494:pharmacology*; D010882:Piperonyl Butoxide / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011722:Pyrethrins / Q000494:pharmacology; D013997:Time Factors; D014329:Tropical Climate
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009570:Nitriles; D009574:Nitro Compounds; D010574:Pesticide Synergists; D011720:Pyrazoles; D011722:Pyrethrins; C082359:imidacloprid; C099952:bifenthrin; D003634:DDT; D010882:Piperonyl Butoxide; C082360:fipronil; C037304:cyhalothrin; D005278:Fenitrothion